Multicast is a point to multipoint service in a network where different subscribers have to subscribe to a multicast group. Multicast technique generally is used by applications that want to reach a group of like-minded receivers who normally are not known by the sender in advance.
Multicast technique is well suitable for radio or TV broadcasting. Transmission of sound or image will become popular also in a wireless network in future when the UMTS (Universal Mobile Telecommunications System) technology will provide needed capacity. A multicast address identifies a group of interfaces or subscribers. Data packets that are sent to a multicast address are supplied to all of the interfaces or subscribers of the group by means of the Internet Group Management Protocol (IGMP).
However, according to conventional multicast technique it is not possible to consider different needs of different subscribers belonging to a multicast group.